Generally, in an image forming apparatus of an electrophotographic system, a toner remaining amount sensor is disposed in a developing device. The toner remaining amount sensor obtains toner empty information in the developing device, and when toner empty becomes definite, forcible toner supply from a toner cartridge is performed at the time of warm-up after power-on.
Accordingly, when the toner empty in the developing unit becomes definite, also when power is turned OFF in the state where the toner cartridge has no toner and the toner cartridge is not replaced, the forcible toner supply is performed, and the life of a photoreceptor is reduced by the unnecessary supply operation. Besides, also at the time of return from a sleep mode (power-saving mode), since the forcible toner supply is performed again, a print operation is stopped by the unnecessary supply operation, and the user is required to wait before operating.